The present disclosure relates to a system and method of generating a data file from a point cloud for use in a virtual reality system, and in particular to a system and method of annotating a point cloud with user defined content
Three-dimensional point cloud data may be generated using a three-dimensional (3D) coordinate measurement instrument. A 3D coordinate measurement instruments include, but are not limited to: a laser scanner time-of-flight (TOF) device, a triangulation scanner device, a laser tracker and an articulated arm coordinate measurement machine.
A 3D laser scanner TOF device steers a beam of light to a non-cooperative target such as a diffusely scattering surface of an object. A distance meter in the device measures a distance to the object, and angular encoders measure the angles of rotation of two axles in the device. The measured distance and two angles enable a processor in the device to determine the 3D coordinates of the target. Laser scanners are typically used for scanning closed or open spaces such as interior areas of buildings, industrial installations and tunnels. They may be used, for example, in industrial applications and accident reconstruction applications. A laser scanner optically scans and measures objects in a volume around the scanner through the acquisition of data points representing object surfaces within the volume. Such data points are obtained by transmitting a beam of light onto the objects and collecting the reflected or scattered light to determine the distance, two-angles (i.e., an azimuth and a zenith angle), and optionally a gray-scale value. This raw scan data is collected, stored and sent to a processor or processors to generate a 3D image representing the scanned area or object.
Generating an image requires at least three values for each data point. These three values may include the distance and two angles, or may be transformed values, such as the x, y, z coordinates. In an embodiment, an image is also based on a fourth gray-scale value, which is a value related to irradiance of scattered light returning to the scanner. A 3D image of a scene may require multiple scans from different registration positions. The overlapping scans are registered in a joint coordinate system. Such registration is performed by matching targets in overlapping regions of the multiple scans. The targets may be artificial targets such as spheres or checkerboards or they may be natural features such as corners or edges of walls.
The collection of 3D coordinate data is typically referred to as a point cloud since the coordinates are graphically represented as individual points on surfaces when displayed on a two-dimensional (2D) display, such as a computer monitor. It should be appreciated that it may be difficult to visualize a 3D image of the scene on a 2D display based on the point cloud. To compensate for this methods have been developed to represent surfaces based on the point cloud to create a more realistic visualization. However, the scene is still being represented on a 2D display, which interferes with the user's ability to immerse themselves in the representation of the scanned scene.
Accordingly, while point cloud display systems are suitable for their intended purposes, there is a need for apparatus and methods that allow a user to visualize point cloud data and user defined data in a virtual environment according to certain features of embodiments of the present invention.